/in/calc.cpp:142:48: error: '&&' within '||' [-Werror,-Wlogical-op-parentheses]
        if (input[0] == '-' || '0' <= input[0] && input[0] <= '9') {
                            ~~ ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~
/in/calc.cpp:142:48: note: place parentheses around the '&&' expression to silence this warning
        if (input[0] == '-' || '0' <= input[0] && input[0] <= '9') {
                                               ^
                               (                                 )
1 error generated.
/in/Compile/Makefile:44: recipe for target 'buildCalc' failed
make: *** [buildCalc] Error 1